Commercial transport aircraft typically include service galleys for preparing meals and refreshments for passengers and crew. A typical service galley includes a number of electrical appliances or “inserts” such as ovens, coffee makers, trash compactors, and air chillers. Each of the appliances is independently connected to a power feeder that receives electrical power from an aircraft power source. Although most galley appliances operate in a cyclic nature, or for only short periods of time, the electrical power feeder must be sized to support a worst-case load event in which all of the appliances are operating at the same time. Sizing the power feeder for this worst-case scenario results in a relatively heavy and relatively expensive power feeder.
Conventional transport aircraft typically allocate a preset amount of electrical power for galley operations. For example, a typical passenger jet may allocate between 90 and 100 KVA (Kilovolt-Amperes) for such operations. If a particular airline customer selects a suite of galley equipment that could potentially exceed the allocation of electrical power, then interlocks are incorporated into the galley power circuit to prevent an overload. Interlocks are switches that allow flight attendants to make power available to one appliance or one group of appliances, but not another appliance or another group of appliances. In this way, power is available for only a subset of the galley appliances at any given time, thereby preventing the possibility of exceeding the power allocation. One downside of interlocks, however, is that they result in customization of the aircraft galley and additional complexity. Further, they require flight attendants to manually coordinate usage of various galley appliances. Having to manually coordinate appliance usage in this way often impacts the ability of the flight attendants to provide in-flight service in an efficient manner. In addition, this coordination increases flight attendant workload and may increase flight attendant training requirements.
Electric power to galley systems on a conventional jet aircraft is typically cut off when the aircraft experience a significant power shortage. This event is referred to as a “load shed.” When power is restored, the galley appliances may or may not, depending on the specific type of appliance, resume operation. One downside associated with load sheds is that flight attendants must guess at how to reset oven timers and other appliance settings to complete food preparation once power has been restored.
Conventional transport aircraft typically use engine bleed air to drive hydraulic pumps, cabin pressurization equipment, anti-ice systems, and other aircraft systems. Running these systems on electric power from the engines, however, instead of engine bleed air may increase the fuel efficiency and thus lower the operating cost of the aircraft. However, increasing the number of aircraft systems using electric power may reduce the amount of electric power available for galley operations. For example, if a typical jet transport aircraft today allocates between 90 and 100 KVA for galley operations, in the future a comparable “more electric” aircraft may only allocate between 40 and 70 KVA for such operations. Accordingly, developing galley systems that use less aircraft power is an important step in the development of fuel efficient “more electric” aircraft.